Patches for Berkeley DB version 4.6.21

[#15692] Fixes a race condition between checkpoint and DB->close which can result in the checkpoint thread self-deadlocking.Download patch file

[#16178] Fixes the potential for the wrong number of mutexes to be allocated. This issue could cause applications with multiple cache regions to see undefined behavior in rare cases under load.Download patch file

[#15788] Fixes a bug which could lead to slow performance of internal init under Replication Manager, as evidenced by "queue limit exceeded" messages in verbose replication diagnostic output.Download patch file